In many integrated circuits (ICs), power rails are used to distribute power to functional circuit elements formed in a substrate. Power is often delivered to power rails using metal layers between the power rails and power straps at a level above the level of the power rails.
The resistance of an IC structure including such metal layers can affect the efficiency of power delivery, heat generation, and susceptibility to electromigration (EM). Routing of the metal layers can also impact the routing of additional electrical connections to the functional circuit elements.